Evidence is rapidly growing to link adverse health effects in divergent natural species and humans located in similar exposure areas. In addition to natural exposures, the interactions of chemical contamination and purification byproducts in drinking water and the relationships to health need to be evaluated. Our objective is to provide a mechanistic understanding of variables associated with environmentally-induced mutation in rodent and alternative/environmental sentinel models. Initially we have used a bacteriophage with selective reverse mutant detection markers as a transgenic indicator in fish, mice and cells; there is no expression of the phage and recovery of the sequence from each cell means that the use of animals can be greatly reduced. Selective mutant detection helps to reduce the biological variability that might be associated with phenotypic comparisons between species. We have demonstrated production of two transgenic aquatic species Oryzias latipes (medaka, freshwater), and Fundulus heteroclitus (mummichog, saltwater); both are used extensively for environmental and laboratory studies.We have demonstrated that the spontaneous mutation frequencies for in vitro cells and tissues of fish were similar to mice and ranged between 1.8- 3.7x10-7. Significant increases in mutation of the transgene were observed in mice and fundulus after exposure to ENU. Taken together, these results indicate an identical gene target can be used in aquatic species, laboratory mammals and a variety of cultured cells in studies designed to provide a sound basis for extrapolation between various animal and alternative models. Our current experiments seek to define the relationships of metabolic activation, metabolites and stable/unstable DNA adduction directly with mutation and carcinogenesis at dose parity in mice and fundulus for a polycyclic aromatic hydrocarbon (DMBA). We are also collaborating with Army to expand the medaka model and explore integration of field and laboratory applications to complex mixtures.